Author(s): Sarah Dickel; Stephan Theobald

Linked Author(s): Sarah Dickel, Stephan Theobald

Keywords: Flood Protection; Intelligent Control; Cascades of Hydropower Plants

Abstract: Like many rivers in the world, most big streams in Germany and Austria are developed with cascades of run-of-river hydropower plants, meeting various operational objectives, such as power generation, navigation or flood protection. Especially big flood events like the flood of June 2013 at the Danube basin are raising the important question whether it is possible to use the reservoirs of the run-of-river plants for the reduction of flood peaks by defining an intelligent control for the plants. Comparatively low heads and no large reservoirs characterize these impounded rivers. Possible flood mitigation measures are manifold and constantly under discussion by research and the public with regard to feasibility and effect. In order to investigate various measures for the Bavarian Inn as the largest German tributary of the Danube, a study on retention potential was commissioned by the Bavarian State Office for the Environment, in which the adapted management of the plants was also investigated by the Department of Hydraulic Engineering and Water Resources Management of Kassel University. The effectiveness of barrage management, which can be implemented without major structural changes, has been constantly questioned and was investigated in detail in this study. The conducted investigations show that for the Bavarian Inn (210 km, 15 power plants in total with max. heads about 10 m, max. 100-year flood 6800 m³/s) a potential to reduce flood peaks with an adapted control can be given. Furthermore, they are pointing out that a good process understanding of the interaction between the operation of the hydropower plants and the flow characteristics of the examined river is needed. Extensive analyses and sensitivity studies for a large variety of parameters and measured values are also necessary as well as performing the examination based on operationally available data. Only by considerating all named aspects using a complex model system, it is ultimately possible to define control options relevant for real operations. The study is carried out using a 1D hydrodynamic numerical model, covering over 260 km of streams with different lateral inflows, which is implemented into MATLAB/Simulink to integrate control systems and automation features. While using practicable values for drawdowns and gradients plus defining the process based on operationally available values, a reduction up to 9 % can be achieved, depending on the height and shape of the flood wave. This corresponds to a reduction of the maximum water level of up to about 35 cm in the estuary area of Inn and Danube, which can have great influence on flooded areas, with a retained volume of up to 20 million m³ in the peak area of the flood. Based on detailed investigations, the methodology applied can be and is currently being transferred to other river systems.

DOI: https://doi.org/10.3850/IAHR-39WC252171192022758

Year: 2022